WO2017115871A1 - 円環状のガラス素板、円環状のガラス素板の製造方法、円環状のガラス基板の製造方法、及び磁気ディスク用ガラス基板の製造方法 - Google Patents

円環状のガラス素板、円環状のガラス素板の製造方法、円環状のガラス基板の製造方法、及び磁気ディスク用ガラス基板の製造方法 Download PDF

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Publication number
WO2017115871A1
WO2017115871A1 PCT/JP2016/089203 JP2016089203W WO2017115871A1 WO 2017115871 A1 WO2017115871 A1 WO 2017115871A1 JP 2016089203 W JP2016089203 W JP 2016089203W WO 2017115871 A1 WO2017115871 A1 WO 2017115871A1
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WO
WIPO (PCT)
Prior art keywords
base plate
glass base
main surface
plate
annular
Prior art date
Application number
PCT/JP2016/089203
Other languages
English (en)
French (fr)
Japanese (ja)
Inventor
修平 東
Original Assignee
Hoya株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Hoya株式会社 filed Critical Hoya株式会社
Priority to MYPI2018701605A priority Critical patent/MY188163A/en
Priority to CN201680067880.1A priority patent/CN108292510B/zh
Priority to SG11201804418PA priority patent/SG11201804418PA/en
Priority to JP2017559253A priority patent/JP6385595B2/ja
Publication of WO2017115871A1 publication Critical patent/WO2017115871A1/ja

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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/62—Record carriers characterised by the selection of the material
    • G11B5/73—Base layers, i.e. all non-magnetic layers lying under a lowermost magnetic recording layer, e.g. including any non-magnetic layer in between a first magnetic recording layer and either an underlying substrate or a soft magnetic underlayer
    • G11B5/739—Magnetic recording media substrates
    • G11B5/73911—Inorganic substrates
    • G11B5/73921—Glass or ceramic substrates
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
    • G11B5/8404—Processes or apparatus specially adapted for manufacturing record carriers manufacturing base layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28D—WORKING STONE OR STONE-LIKE MATERIALS
    • B28D1/00—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor
    • B28D1/22—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor by cutting, e.g. incising
    • B28D1/24—Working stone or stone-like materials, e.g. brick, concrete or glass, not provided for elsewhere; Machines, devices, tools therefor by cutting, e.g. incising with cutting discs
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B33/00—Severing cooled glass
    • C03B33/02—Cutting or splitting sheet glass or ribbons; Apparatus or machines therefor
    • C03B33/023—Cutting or splitting sheet glass or ribbons; Apparatus or machines therefor the sheet or ribbon being in a horizontal position
    • C03B33/027—Scoring tool holders; Driving mechanisms therefor
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B33/00—Severing cooled glass
    • C03B33/02—Cutting or splitting sheet glass or ribbons; Apparatus or machines therefor
    • C03B33/04—Cutting or splitting in curves, especially for making spectacle lenses
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B33/00—Severing cooled glass
    • C03B33/09—Severing cooled glass by thermal shock
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
    • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers

Definitions

  • the present invention relates to an annular glass base plate, an annular glass base plate manufacturing method, an annular glass substrate manufacturing method, and a magnetic disk glass substrate manufacturing method.
  • a personal computer, a DVD (Digital Versatile Disc) recording device, and the like have a built-in hard disk device (HDD: Hard Disk Drive) for data recording.
  • HDD Hard Disk Drive
  • a hard disk device a magnetic disk having a magnetic layer provided on a substrate is used, and magnetic recording information is recorded on or read from the magnetic layer by a magnetic head slightly floated on the surface of the magnetic disk.
  • a glass substrate having a property that is less likely to be plastically deformed than a metal substrate (aluminum substrate) or the like is preferably used.
  • the glass substrate for a magnetic disk is manufactured by preparing an annular glass base plate from a plate-shaped glass base plate and subjecting the annular glass base plate to mechanical processing such as grinding and polishing.
  • mechanical processing such as grinding and polishing.
  • a method of cutting a plate-shaped glass base plate formed by a float method, a downdraw method, etc. into an annular shape, and a glass plate by pressing a lump of molten glass with a pair of press molds A method of cutting a base plate into an annular shape is known.
  • a method in which a circular cut line is formed on a glass plate, and then a region outside the cut line of the glass plate is heated to cut out a region inside the cut line in a circular shape (Patent Literature). 1).
  • a circular incision for forming an outer shape and a circular incision for forming an inner hole are formed on one main surface of the plate-like glass base plate. Thereafter, these cut lines are grown to cleave the plate-like glass base plate, thereby forming an annular glass base plate.
  • an outer cutter wheel for forming an outer incisor and an inner cutter wheel for forming an inner incisor are pressed against one main surface of a plate-like glass base plate.
  • the cutter wheel and the plate-shaped glass base plate are relatively rotated.
  • the roundness of the outer incisor deteriorates and the concentricity of the outer incisor and the inner incisor decreases. If the concentricity between the outer and inner incisors is low, it is necessary to increase the machining allowance in order to ensure the concentricity of the outer peripheral shape of the magnetic disk glass substrate and the inner hole. There is a problem of getting worse.
  • the inner cut line is caused by the difference in thermal expansion. It grows and reaches the other main surface (second main surface) opposite to the one main surface (first main surface). Thereafter, by removing the glass other than the target portion, it is possible to take out the annular glass base plate from the plate-like glass base plate. Thereafter, the inner peripheral edge and the outer peripheral edge of the annular glass base plate are chamfered by grinding with a general-purpose grindstone or the like, thereby having a chamfered surface and a side wall surface on the inner periphery and the outer periphery, respectively. An annular glass substrate is formed.
  • the outer incision and the inner incision A phenomenon was observed in which the angles extending from the first main surface in the depth direction differed. More specifically, with respect to the direction (angle) extending in the depth direction of the outer cut line and the inner cut line formed in a circle on the first main surface of the plate-shaped glass base plate, the direction of the inner cut line is A phenomenon of tilting toward the center of the circle rather than the direction of the outer incisor was observed.
  • the present invention is an annular glass base plate capable of increasing the processing efficiency of the glass base plate to increase the production efficiency of the glass substrate, a manufacturing method of the annular glass base plate, a manufacturing method of the annular glass substrate, And it aims at providing the manufacturing method of the glass substrate for magnetic discs.
  • the present invention includes the following forms.
  • the plate-like glass is formed by forming outer and inner incisors on the surface of the plate-like glass base plate, and causing the outer and inner incisors to advance in the thickness direction of the plate-like glass base plate.
  • the first interval is preferably 5 to 40 ⁇ m.
  • the second interval is preferably 10 to 80 ⁇ m.
  • the maximum depth of the first notch is preferably 3 to 15 ⁇ m.
  • the circumferential interval, length, and depth of the cutouts of the first and second circular blades can be appropriately selected according to the rotation radius of the first and second circular blades. As the radius of rotation of the circular blade increases, it is preferable to decrease the notch interval, increase the length of the notch, and increase the depth of the notch.
  • the length of the circumferential direction of the said 1st notch is a manufacturing method of the annular
  • the circumferential length of the first notch is, for example, 5 to 60 ⁇ m.
  • the length of the circumferential direction of the said 1st notch is a manufacturing method of the annular
  • the cutting edge ridge of the first circular blade has a first inner inclined surface closer to the rotation center than the first plane including the cutting edge ridge line of the first circular blade, and the first flat surface with respect to the first flat surface. Formed by a first outer inclined surface opposite to the rotation center;
  • the cutting edge ridge of the second circular blade has the second inner inclined surface closer to the rotation center than the second plane including the cutting edge ridge line of the second circular blade, and the second plane.
  • An annular glass base plate that is an element of an annular glass substrate, The glass base plate has an inner peripheral end face made of a circular hole in the center, and an outer peripheral end face, A concentricity between the inner peripheral end surface and the outer peripheral end surface is a glass base plate of 15 ⁇ m or less.
  • An annular glass base plate that is an element of an annular glass substrate, A first main surface and a second main surface opposite to the first main surface; The glass base plate, wherein a difference between the roundness of the outer peripheral shape of the first main surface and the roundness of the outer peripheral shape of the second main surface is 100 ⁇ m or less.
  • Outer incisions and inner incisions are formed on the main surface of a plate-shaped glass base plate made of a glass material having a linear expansion coefficient of 65 ⁇ 10 ⁇ 7 / ° C. or less, and the outer incisions and the inner incisors are connected to the plate.
  • the shape processing is The first circular blade and the second circular blade brought into contact with one main surface of the plate-like glass base plate are relatively rotated around the main surface and one rotation center, whereby the first Forming a circular outer cutting line on the main surface with one circular blade, and forming a circular inner cutting line on the main surface with a smaller radius than the outer cutting line with the second circular blade.
  • the cutting edge ridge of the first circular blade has a first inner inclined surface closer to the rotation center than the first plane including the cutting edge ridge line of the first circular blade, and the first flat surface with respect to the first flat surface.
  • the cutting edge ridge of the second circular blade has the second inner inclined surface closer to the rotation center than the second plane including the cutting edge ridge line of the second circular blade, and the second plane.
  • the first circular blade and the second circular handle are: ⁇ 2> 0 and ⁇ 1 ⁇ 2 Satisfy the relationship The first circular blade and the second circular handle are brought into contact with the main surface so that an angle formed with the main surface of the first plane is the same as an angle formed with the main surface of the second plane.
  • An annular glass base plate The glass base plate has an inner peripheral end face made of a circular hole in the center, and an outer peripheral end face, The glass base plate, wherein each of the inner peripheral end surface and the outer peripheral end surface includes a split cross section, and a difference in angle with respect to a main surface of each of the inner peripheral end surface and the outer peripheral end surface is 10 ° or less in a cross-sectional view.
  • the roundness of the outer cut line formed by the first circular blade can be improved, and the concentricity between the inner cut line and the outer cut line formed by the second circular blade can be increased. Can be increased. For this reason, the concentricity of the outer peripheral end surface consisting of the split cross-section extending from the outer cut and the inner peripheral end surface consisting of the split cross-section extending from the inner cut can be increased. Therefore, it is possible to reduce the machining allowance in subsequent processes such as chamfering processing and end surface polishing processing on the outer peripheral end surface and the inner peripheral end surface, and it is possible to increase the processing efficiency of the annular glass base plate. The production efficiency of a glass substrate such as a magnetic disk glass substrate can be increased.
  • the processing efficiency of the glass base plate can be increased, and further, the production efficiency of an annular glass substrate, for example, a magnetic disk glass substrate can be increased.
  • FIG. 3 is a cross-sectional view taken along arrow III-III in FIG. 2.
  • FIG. 4 is a view taken along arrow IV in FIG. 2.
  • FIG. 6 is a cross-sectional view taken along the line VI-VI in FIG. 5. It is a VII arrow line view of FIG.
  • FIG. 10B It is a perspective view which shows an example of the annular
  • the glass substrate used by this embodiment is not limited to the glass substrate for magnetic discs, It can apply to various annular
  • the size of the magnetic disk glass substrate applied as an example in the present embodiment is not particularly limited. For example, a nominal 2.5 inch size (outer diameter of about 65 mm, circular hole diameter of about 20 mm). It is suitable for manufacturing the above glass substrate for magnetic disk. A nominal 3.5-inch size (outer diameter of about 95 mm, circular hole diameter of about 25 mm) or more is more preferable because the effect of reducing the machining allowance becomes larger.
  • the thickness of the plate is not particularly limited, but it is suitable for manufacturing a glass substrate for a magnetic disk having a thickness of 0.4 to 2.0 mm, for example.
  • the glass substrate for magnetic disks has a disk shape.
  • the glass substrate for magnetic disk has a circular central hole concentric with the outer periphery.
  • a magnetic disk is formed by forming magnetic layers (recording areas) in the annular areas on both sides of the glass substrate for a magnetic disk.
  • the glass base plate for a magnetic disk is an annular glass base plate before a polishing process described later is performed.
  • Annular means having a substantially circular outer shape and having a substantially circular inner hole.
  • substantially circular includes a perfect circle shape and an ellipse shape, and its outer peripheral shape may consist only of a single arc of curvature radius, or consist of arcs or curves of different curvature radii. It may be.
  • a circular outer shape forming outer cut line and a circular inner hole forming inner cut line are formed on one main surface (scribe surface) of a plate-like glass base plate. (Scribing). Thereafter, these cut lines are grown to the other main surface to cleave the plate-like glass base plate, thereby forming an annular glass base plate (cleaving treatment).
  • the plate-like glass base plate can be formed by, for example, cutting a plate glass formed by a float method or an overflow downdraw method into a predetermined size. Moreover, you may form a disk-shaped glass base plate by press-molding a molten glass lump.
  • Aluminosilicate glass, soda lime glass, borosilicate glass, etc. can be used as the material of the glass base plate.
  • aluminosilicate glass can be suitably used in that it can be chemically strengthened and a glass substrate for a magnetic disk excellent in the flatness of the main surface and the strength of the substrate can be produced.
  • the scribing process is a process of providing a circular cutting line on one main surface (scribe surface) of the glass base plate with a cutter (scriber) made of super steel alloy or containing diamond particles.
  • a circular cutting line (inner cut line) that becomes the outline of the circular hole and a circular cutting line (outer cut line) that becomes the outer outline of the glass base plate are formed simultaneously.
  • the outer incisor and the inner incisor are formed so as to be concentric.
  • the cleaving process is a method of extending the circular cutting line formed by the scribing process in the thickness direction (depth direction) of the glass base plate and separating the outside or the inside of the circular cutting line.
  • the cutting line can be extended by the difference in thermal expansion by heating or cooling at least a part of the glass base plate.
  • the outer part or the inner part may be pressed in a direction perpendicular to the main surface from the circular cutting line.
  • An annular glass base plate can be obtained by separating and removing a portion outside the outer cut line and a portion inside the inner cut line of the glass base plate.
  • FIG. 1 is an elevation view showing an example of a scribing apparatus 1 for cutting an annular glass base plate from a plate-like glass base plate 10A.
  • the scribing apparatus 1 includes a table 2, an outer cutter wheel 3 (first circular blade), an inner cutter wheel 4 (second circular blade), and the like.
  • the table 2 is a support base that supports the plate-shaped glass base plate 10A.
  • the table 2 rotates the plate-like glass base plate 10A around the rotation center A1 perpendicular to the main surface of the plate-like glass base plate 10A relative to the outer cutter wheel 3 and the inner cutter wheel.
  • the outer cutter wheel 3 and the inner cutter wheel 4 may be rotated around the rotation center A1 while the table 2 and the plate-shaped glass base plate 10A are stationary, and the outer cutter wheel 3 and the inner cutter wheel 4 may be rotated.
  • the table 2 and the plate-shaped glass base plate 10A may be rotated around the rotation center A1 in a stationary state.
  • an unillustrated adsorption portion that adsorbs the glass base plate 10 ⁇ / b> A may be provided on the table 2.
  • a suction portion that sucks the plate-shaped glass base plate 10 ⁇ / b> A placed on the upper surface of the table 2 is provided at the center of the table 2.
  • an annular recess is provided on the upper surface of the table 2 so as to surround the center portion where the suction portion is provided, and a center support portion is provided in a portion surrounded by the annular recess, and the annular recess
  • An outer peripheral support portion is provided at an outer peripheral portion surrounding the.
  • the center support portion and the outer periphery support portion are provided so as to protrude upward with respect to the annular recess, and the plate-like glass base plate 10A is supported by the center support portion and the outer periphery support portion.
  • the adsorption part is configured to be fixed on the table 2 by adsorbing the plate-like glass base plate 10A supported by the center support part and the outer periphery support part.
  • the upper surface of the glass base plate 10 ⁇ / b> A placed on the upper part of the table 2 is a first main surface (scribe surface) on which the outer score 11 and the inner score 12 are formed, and is in contact with the table 2.
  • the lower surface of the base plate 10A is the second main surface (non-scribe surface).
  • the glass base plate 10A may be supported by sandwiching the glass base plate 10A at the outer periphery.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are disk-shaped cutters (circular blades) made of super steel alloy or made of diamond particles.
  • the first embodiment and the second embodiment of the scribing apparatus 1 will be described in detail.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are configured in consideration of the following circumstances. That is, as shown in FIG. 1, when forming the cut line on the plate-shaped glass base plate 10 ⁇ / b> A, the outer cutter wheel 3 that forms the outer cut line 11 is more than the inner cutter wheel 4 that forms the inner cut line 12. The mileage is long. When the outer cutter wheel 3 and the inner cutter wheel 4 are rotated with respect to the plate-shaped glass base plate 10 ⁇ / b> A at the same angular speed, the outer cutter wheel 3 has a higher traveling speed than the inner cutter wheel 4, and the outer cutting line 11. The contact time with the outer cutter wheel 3 per unit length is shorter than the contact time with the inner cutter wheel 4 per unit length of the inner cutting line 12.
  • the outer cutter wheel 3 having a larger rotation radius with respect to the glass base plate 10 ⁇ / b> A is more likely to cause a change in the direction of the force in the rotational radius direction with respect to the glass base plate 10 ⁇ / b> A than the inner cutter wheel 4. It is presumed that the variation of the direction becomes large. Then, this inventor thought that the concentricity of the outer incisor 11 and the inner incisor 12 can be improved by improving the ease of biting into the glass base plate 10A of the outer cutter wheel 3.
  • FIG. 2 is a diagram showing in detail an example of the form of the outer cutter wheel 3 in the first embodiment, and is an enlarged view of a portion II in FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2, and FIG. 4 is a view taken along the arrow IV in FIG.
  • an outer edge of the outer cutter wheel 3 is provided with a cutting edge ridge 31 in an annular shape.
  • a plurality of notches 32 are provided in the cutting edge ridge 31 with a predetermined interval (first interval C1) in the circumferential direction.
  • the outer cutter wheel 3 is in a state in which the cutting edge ridge 31 is pressed against the upper main surface (first main surface) of the plate-like glass base plate 10A with respect to the plate-like glass base plate 10A around the rotation center A1. And rotate relative to each other. At this time, the outer cutter wheel 3 rotates around the rotation axis A2 parallel to the rotation radius direction around the rotation center A1. The outer main cutter wheel 3 rotates around the rotation axis A2 while rotating and moving relative to the plate-like glass base plate 10A around the rotation center A1, so that the upper main surface of the plate-like glass base plate 10A is rotated.
  • the outer incisor 11 is formed at a portion in contact with the cutting edge ridge 31.
  • the distance from the rotation center A1 to the cutting edge ridge 31 at this time is a rotation radius (first rotation radius R1) around the rotation center A1 of the outer cutter wheel 3, and the plate-like glass element is formed by the first rotation radius R1.
  • the radius of the outer shape of the annular glass base plate cut out from the plate 10A is determined.
  • FIG. 5 is a diagram showing details of an example of the inner cutter wheel 4 in the first embodiment, and is an enlarged view of a portion V in FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. 5, and FIG. 7 is a view taken along arrow VII in FIG.
  • an annular cutting edge 41 is provided on the outer peripheral portion of the inner cutter wheel 4 in an annular shape.
  • the cutting edge ridge 41 is provided with a plurality of notches 42 (second notches) with a predetermined interval (second interval C2) in the circumferential direction.
  • the inner cutter wheel 4 rotates relative to the plate-shaped glass base plate 10A around the rotation center A1 in a state where the cutting edge ridge 41 is pressed against the upper main surface of the plate-like glass base plate 10A. .
  • the inner cutter wheel 4 rotates around the rotation axis A3 parallel to the rotation radius direction around the rotation center A1.
  • the upper main surface of the plate-shaped glass base plate 10A is rotated by the inner cutter wheel 4 rotating about the rotation axis A3 while rotating and moving relative to the plate-shaped glass base plate 10A around the rotation center A1.
  • the inner incisor 12 is formed at a portion in contact with the cutting edge ridge 41.
  • the distance from the rotation center A1 to the cutting edge ridge 41 at this time is the rotation radius (second rotation radius R2) around the rotation center A1 of the inner cutter wheel 4, and the plate-like glass element is formed by the second rotation radius R2.
  • the radius of the inner hole of the annular glass base plate cut out from the plate 10A is determined.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are pressed against the upper main surface of the plate-shaped glass base plate 10 ⁇ / b> A placed on the table 2.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are rotated and moved relative to the plate-shaped glass base plate 10A around the rotation center A1.
  • the load on the outer cutter wheel 3 during this period is preferably 50 to 100% of the load on the inner cutter wheel 4.
  • the outer cut line 11 and the inner cut line 12 are formed on the upper main surface of the plate-shaped glass base plate 10A.
  • the outer cutter wheel 3 is arranged on the same side as the inner cutter wheel 4 with respect to the rotation center A1. That is, the outer cutter wheel 3 and the inner cutter wheel 4 are arranged at the same phase position with respect to the rotation center A1.
  • the present embodiment is not limited to this, and the outer cutter wheel 3 and the inner cutter wheel 4 may be arranged on the opposite side with respect to the rotation center A1. That is, you may arrange
  • the first notch 32 and the second notch 42 are formed so that the first interval C1 is smaller than the second interval C2.
  • the contact area of the outer cutter wheel 3 to the upper main surface of the plate-shaped glass base plate 10A becomes smaller than the contact area of the inner cutter wheel 4.
  • the pressure of the outer cutter wheel 3 to the upper main surface of the plate-shaped glass base plate 10A is changed to the inner cutter wheel. 4
  • the outer cutter wheel 3 is likely to bite (or bite) deeply from the upper main surface of the plate-like glass base plate 10 ⁇ / b> A into the glass base plate 10 ⁇ / b> A.
  • C2-C1 is, for example, 5 to 75 ⁇ m.
  • the first interval C1 is preferably 5 to 40 ⁇ m.
  • the second distance C2 is preferably 10 to 80 ⁇ m. If the second distance C2 is less than 10 ⁇ m, the blade of the inner cutter wheel 4 may be easily applied. On the other hand, if it exceeds 80 ⁇ m, the inner cutter wheel 4 may not be sufficiently bitten when forming the inner peripheral cut line 12.
  • the difference between the first interval C1 and the second interval C2 is preferably at least 5 ⁇ m or more and preferably 10 ⁇ m or more in order to ensure sufficient biting of the outer cutter wheel 3 at the time of forming the outer peripheral cutting line 11. And more preferred. Moreover, although there is no upper limit in particular regarding the said difference, it is preferable that it is 75 micrometers or less from a viewpoint of durability of the front-end
  • the circumferential length L1 of the first notch 32 is longer than the circumferential length L2 of the second notch 42.
  • the circumferential length L1 of the first notch 32 is, for example, 5 to 60 ⁇ m.
  • the circumferential length L2 of the second notch 42 is, for example, 2 to 30 ⁇ m.
  • the difference in the circumferential length between the first notch 32 and the second notch 42 is not particularly required, but is preferably 10 ⁇ m or more, and more preferably 15 ⁇ m or more. Moreover, although there is no upper limit in particular about the said difference, it is preferable that it is 50 micrometers or less from a viewpoint of forming the cut line 11 of an outer peripheral side stably especially.
  • the maximum depth D1 of the first notch 32 is preferably deeper than the maximum depth D2 of the second notch 42.
  • the maximum depth D2 of the second notch 42 is preferably, for example, 1 to 15 ⁇ m. If the thickness is less than 1 ⁇ m, the inner cutter wheel 4 may not be sufficiently bite when the cut line 12 is formed. Moreover, when it exceeds 15 micrometers, there exists a possibility that the blade of the inner side cutter wheel 4 may become easy to apply.
  • the difference D1-D2 in the maximum depth between the first notch 32 and the second notch 42 is not particularly required, but is preferably 1 ⁇ m or more, and more preferably 2 ⁇ m or more.
  • the upper limit of the difference is not particularly limited, but is preferably 10 ⁇ m or less from the viewpoint of durability of the outer cutter wheel 3.
  • the notch 32 is formed so that the circumferential length L1 of the notch 32 is longer than the first interval C1.
  • L1> C1 the contact area of the outer cutter wheel 3 with the main surface on the upper side of the plate-like glass base plate 10A becomes small, so that when a force is applied downward to the outer cutter wheel 3, the plate-like glass The pressure of the outer cutter wheel 3 on the upper main surface of the glass base plate 10A is increased, and the outer cutter wheel 3 is likely to bite deeply into the glass base plate 10A from the upper main surface of the plate-like glass base plate 10A.
  • L1-C1 is, for example, 10 to 40 ⁇ m.
  • the notch 42 is formed so that the circumferential length L2 of the notch 42 is shorter than the second interval C2.
  • L2 ⁇ C2 the contact area of the inner cutter wheel 4 to the upper main surface of the plate-like glass base plate 10A increases, so that when a force is applied downward to the inner cutter wheel 4, the plate-like glass The pressure of the inner cutter wheel 4 on the upper main surface of the glass base plate 10A is reduced, and the inner cutter wheel 4 is less likely to bite into the glass base plate 10A from the upper main surface of the plate-like glass base plate 10A. For this reason, the outer cutter wheel 3 can easily bite deeply into the glass base plate 10A from the main surface on the upper side of the plate-like glass base plate 10A.
  • C2-L2 is, for example, 5 to 30 ⁇ m.
  • FIG. 8 is a perspective view showing an annular glass base plate 10B obtained as described above.
  • the annular glass base plate 10 ⁇ / b> B has an outer peripheral end surface 13, an inner peripheral end surface 14, a first main surface 15, and a second main surface 16.
  • the outer peripheral end face 13 is a fractured cross section in which the outer cut line 11 of the plate-like glass base plate 10A has advanced to reach the second main surface.
  • the inner peripheral end surface 14 is a fractured section in which the inner cut line 12 of the plate-like glass base plate 10A has advanced to reach the second main surface.
  • the first main surface 15 is a part of the first main surface on which the outer cut line 11 and the inner cut line 12 of the plate-shaped glass base plate 10A are formed (scribe surface).
  • the second main surface 16 is a main surface opposite to the first main surface 15 of the annular glass base plate 10B (non-scribe surface), and is in contact with the table 2 of the plate-like glass base plate 10A. 2 is a part of the main surface.
  • the outer periphery 15A of the first main surface 15 is formed by the outer incisor 11.
  • the outer periphery 16A of the second main surface 16 is formed by the split section extending from the outer cut line 11 reaching the second main surface of the plate-like glass base plate 10A.
  • the inner circumference 15B of the first main surface 15 is formed by the inner incisor 12.
  • the inner periphery 16B of the second main surface 16 is formed by the split section extending from the inner cut line 12 reaching the second main surface of the plate-like glass base plate 10A.
  • the outer cutter wheel 3 and the inner cutter wheel 4 described above it is possible to reduce the variation in the direction (angle) in which the outer cut line 11 extends into the glass base plate 10A in particular, As a result, the variation in the distance from the rotation center A1 of the outer incisor 11 can be reduced, and the concentricity between the outer incisor 11 and the inner incisor 12 can be increased.
  • the concentricity between the outer periphery and the inner periphery of the annular glass base plate 10B formed in this way is preferably 15 ⁇ m or less.
  • the concentricity is represented by the distance between the center of the outer circumference circle and the center of the inner circumference circle.
  • the concentricity can be measured, for example, with a roundness / cylindrical shape measuring machine or the like using an ono-blade probe whose tip is wider than the plate thickness.
  • the outer incisor 11 using the said outer cutter wheel 3, and forming the inner incisor 12 using the inner cutter wheel 4, the outer periphery 15A and the inner periphery 15B of the 1st main surface 15 and The concentricity can be reduced.
  • the concentricity is represented by the distance between the centers of the outer periphery 15A and the inner periphery 15B.
  • the roundness of the outer periphery 15A of the first main surface 15 that is a scribe surface is smaller than the roundness of the outer periphery 16A of the second main surface 16 that is a non-scribe surface.
  • the difference between the roundness of the shape of the outer periphery 15A and the roundness of the shape of the outer periphery 16A is preferably 100 ⁇ m or less from the viewpoint of reducing the machining allowance for the end processing in the subsequent process.
  • roundness means the magnitude of deviation from a geometrically correct circle (geometric circle) in a circular form. Roundness is expressed by the difference in radius between two circles when the interval between the two concentric circles is the minimum when the circular shape is sandwiched between two concentric geometric circles (JIS B0621).
  • the diameter of the probe tip should be sufficiently small, and when using an ono-blade probe with a tip wider than the plate thickness, adjust the angle at which the probe is applied. That's fine.
  • the outer peripheral end face 13 of the annular glass base plate 10B formed from the outer incisor 11 and the inner incisor 12 and The machining allowance in a subsequent process such as chamfering processing or end surface polishing processing for the inner peripheral end surface 14 can be reduced, the processing efficiency of the annular glass base plate can be increased, and further, the annular glass substrate, For example, the production efficiency of a glass substrate for a magnetic disk can be increased.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are configured in consideration of the following circumstances. That is, the cut line formed by pressing the cutter wheels (the outer cutter wheel 3 and the inner cutter wheel 4) toward the first main surface of the glass base plate 10A is in a plane including the cutting edge of the cutter wheel. Is formed so as to extend in a direction away from the cutting edge. For this reason, when the cutter wheel rotates relative to the plate-shaped glass base plate 10A along the main surface, the cut line is formed in a line segment having a predetermined length in contact with the circular orbit of the cutter. When the cutter moves along a circular orbit, this line segment-like cut line is continued along the circular orbit to form a circular cut line.
  • the cut lines extending inside the glass base plate 10A tend to be inclined radially inward from the direction perpendicular to the first main surface.
  • the inner incisor 12 is more intricate than the outer incisor 11 as a result of a complicated influence of a difference in the radius of curvature, a difference in the traveling speed of the cutter, and the like. It is presumed that the film is likely to be inclined toward the inner side in the radial direction from the direction perpendicular to the first main surface.
  • the inclined surface in the center direction of the circular track is arranged so as to be closer to the first main surface than the inclined surface outside the circular track. If the cut line is formed in the state, it is assumed that the formed cut line is formed toward the outside of the circular orbit. Therefore, the present inventor has the inner cutter wheel 4 that forms the inner cutting line 12, and the inclined surface (second inner inclined surface 44) on the center side of the inner cutting line 12 with respect to the cutting edge ridge 41 has a cutting edge ridge.
  • the inner scissors 12 are formed in a state of being arranged closer to the main surface of the plate-like glass base plate 10A than the inclined surface (second outer inclined surface 45) outside the inner scissors 12 than 41, glass is formed.
  • the incision 12 that extends inside the base plate 10A can be reduced from being inclined inward in the radial direction. Accordingly, it was inferred that the split cross section of the inner cut bar 12 and the split cross section of the outer cut bar 11 can be grown in substantially the same direction with respect to the main surface.
  • FIG. 9 is a diagram illustrating details of an example of the outer cutter wheel 3 according to the second embodiment.
  • the cutting edge ridge 31 of the outer cutter wheel 3 is formed by a first inner inclined surface 34 and a first outer inclined surface 35.
  • the first inner inclined surface 34 is closer to the rotation center A1 side than the first plane P1 including the cutting edge ridge 31 that circulates around the outer cutter wheel 3, and the first outer inclined surface 35 is relative to the first plane P1. It is on the side opposite to the rotation center A1.
  • Both of the first inner inclined surface 34 and the first outer inclined surface 35 have the shape of the side surface of the truncated cone so as to approach the rotation axis A2 as the distance from the cutting edge ridge 31 increases.
  • the inner cutter wheel 4 is a disc cutter (circular blade) made of super steel alloy or containing diamond particles, and has an annular cutting edge 41 provided on the outer periphery.
  • the inner cutter wheel 4 has a predetermined radius (second rotation radius R2, R2 ⁇ R1) from the rotation center A1 in a state where the cutting edge ridge 41 is pressed against the first main surface of the plate-shaped glass base plate 10A. It rotates relative to the plate-shaped glass base plate 10A along a circular orbit (second circular orbit). At this time, the inner cutter wheel 4 rotates around the rotation axis A3 parallel to the direction of the second rotation radius R2. The inner cutter wheel 4 rotates about the rotation axis A3 while rotating and moving relative to the plate-like glass base plate 10A along the second circular orbit.
  • the inner incisor 12 is formed at a portion of the main surface 1 that is in contact with the cutting edge ridge 41.
  • the radius of the inner cut line 12 is R2, and the radius of the inner peripheral end surface of the annular glass base plate cut out from the plate-like glass base plate 10A is determined by the second rotation radius R2.
  • FIG. 10 is an enlarged view showing an example of the form of the inner cutter wheel 4 shown in FIG. 1 in the second embodiment.
  • the cutting edge ridge 41 of the inner cutter wheel 4 is formed by a second inner inclined surface 44 and a second outer inclined surface 45.
  • the second inner inclined surface 44 is on the rotation center A1 side with respect to the second plane P2 including the cutting edge ridge 41 that circulates the inner cutter wheel 4, and the second outer inclined surface 45 is with respect to the second plane P2. It is on the side opposite to the rotation center A1.
  • Each of the second inner inclined surface 44 and the second outer inclined surface 45 has the shape of a side surface of a truncated cone that approaches the rotation axis A3 as it moves away from the cutting edge ridge 41.
  • the inner scissors 12 having a trajectory having a smaller radius than the trajectory of the outer scissors 11 tend to be formed so as to incline inward in the radial direction from the main surface of the plate-like glass base plate 10A.
  • the cause is considered as follows.
  • the component force of the plate-shaped glass base plate 10A is from the first inner inclined surface 34 of the outer cutter wheel 3 that moves along the first circular orbit having a smaller curvature than the second circular orbit (having a larger radius of curvature).
  • the force acting on the first main surface is larger than the component force in the direction of the rotation center A1. Therefore, the inner incisor 12 tends to be formed more inclined than the outer incisor 11 toward the rotation center A1 side of the second circular orbit. That is, as shown in FIG.
  • the angle formed by the outer incisor 11 and a straight line extending from the outer incisor 11 toward the center of the first main surface is ⁇ 11, and as shown in FIG. If the angle formed by the straight line from the inner cut line 12 toward the center of the first main surface is ⁇ 12 , ⁇ 12 tends to be smaller than ⁇ 11 .
  • the angle between the first inner inclined surface 34 and the first plane P1 is ⁇ i1
  • the angle between the first outer inclined surface 35 and the first plane P1 is ⁇ o1
  • the second inner inclination is ⁇ i2
  • the angle between the second outer inclined surface 45 and the second plane P2 is ⁇ o2
  • ⁇ 1 ⁇ An angle ⁇ P1 between the outer cutter wheel 3 (first circular blade) and the inner cutter wheel 4 (second circular blade) satisfying the relationship of ⁇ 2 with the first main surface of the first plane P1 is the second plane.
  • the first main surface is brought into contact with the first main surface so as to be equal to the angle ⁇ P2 formed with the first main surface of P2 .
  • the inner scoring line 12 extending inside the glass base plate 10A can be more easily directed from the center to the outer peripheral side of the glass base plate 10A than the direction in which the outer scissor 11 extends inside the glass base plate 10A. It is possible to reduce a tendency that the split section of the inner cut line 12 is formed so as to be inclined inward in the radial direction from the main surface of the plate-shaped glass base plate 10A toward the inside.
  • ⁇ i1, ⁇ o1, ⁇ i2, and ⁇ o2 are each preferably in the range of 40 to 80 °.
  • ⁇ 2 ⁇ 1 is, for example, not less than 5 ° and not more than 30 °.
  • ⁇ i2> ⁇ o2 When the inner cutter wheel 4 is moved along the second circular orbit while the inner cutter wheel 4 is arranged so as to satisfy ⁇ i2> ⁇ o2, the first of the plate-shaped glass base plate 10A is moved from the second inner inclined surface 44.
  • the component of the force acting on the main surface in the direction of the rotation center A1 is the component of the force acting on the first main surface of the plate-like glass base plate 10A from the second outer inclined surface 45 in the outer direction. Power is greater. For this reason, by making ⁇ i2> ⁇ o2, it is possible to make a tendency that the split cross section of the inner incisor 12 is inclined and formed toward the outside of the second circular orbit.
  • ⁇ i2 and ⁇ o2 are preferably 30 ° or less. If it is larger than 30 °, the split cross section of the inner incisor 12 is excessively inclined outward in the radial direction.
  • ⁇ i2 ⁇ o2 is, for example, not less than 5 ° and not more than 30 °.
  • the tendency to be inclined toward the inner side in the radial direction from the main surface of the plate-like glass base plate 10A is smaller than that in the inner incisor 12. Therefore, by setting ⁇ i1 ⁇ i2, the angles of the outer cut 11 and the inner cut 12 extending to the inside of the glass base plate 10A with respect to the main surface of the plate-like glass base plate 10A can be made substantially the same.
  • substantially the same angle means that the difference in angle is less than 10 °. Therefore, the machining allowance for grinding the outer peripheral end face 13 and the inner peripheral end face 14 of the annular glass base plate 10B to obtain the annular glass substrate can be reduced, and the processing efficiency can be increased. .
  • ⁇ i1 ⁇ i2 the cutting resistance when forming the inner incisor 12 can be reduced, and chipping defects around the inner incisor 12 can be reduced.
  • ⁇ i2 ⁇ i1 is, for example, not less than 5 ° and not more than 30 °.
  • the angle ( ⁇ i1 + ⁇ o1) formed by the first inner inclined surface 34 and the first outer inclined surface 35 is preferably smaller than the angle ( ⁇ i2 + ⁇ o2) formed by the second inner inclined surface 44 and the second outer inclined surface 45.
  • ( ⁇ i1 + ⁇ o1) ⁇ ( ⁇ i2 + ⁇ o2) it is possible to reduce cutting resistance when forming the inner incisor 12, and to reduce chipping defects around the inner incisor 12.
  • the angles ( ⁇ i1 + ⁇ o1) and ( ⁇ i2 + ⁇ o2) are preferably adjusted within a range of 100 to 140 °, respectively.
  • the cutter wheel life (number of treatments) may be shortened, and if it is greater than 140 °, the cut line may not be formed well.
  • ( ⁇ i2 + ⁇ o2) ⁇ ( ⁇ i1 + ⁇ o1) is, for example, not less than 5 ° and not more than 30 °.
  • the plate-shaped glass base plate which consists of glass with a small linear expansion coefficient it is preferable to apply 2nd Embodiment. Specifically, it is preferably applied to the shape processing of a plate-shaped glass base plate having a linear expansion coefficient of 65 ⁇ 10 ⁇ 7 / ° C. or less. In particular, the present invention is more preferably applied to shape processing of a glass base plate having a linear expansion coefficient of 50 ⁇ 10 ⁇ 7 / ° C. or less.
  • the linear expansion coefficient is an average thermal expansion coefficient at 50 to 350 ° C.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are pressed against the upper main surface of the plate-shaped glass base plate 10 ⁇ / b> A placed on the table 2.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are set such that the angle ⁇ P1 formed with the upper main surface of the first plane P1 is substantially the same as the angle ⁇ P2 formed with the upper main surface of the second plane P2. Is brought into contact with the upper main surface.
  • the “substantially the same” angle means that the angle difference is within 3 °.
  • the outer cutter wheel so that the first plane P1 is perpendicular to the upper main surface. 3 is preferably brought into contact with the upper main surface.
  • the inner cutter wheel 4 is brought into contact with the upper main surface so that the second plane P2 is perpendicular to the upper main surface. It is preferable.
  • “perpendicular to the upper main surface” means that the angle formed with the normal line of the upper main surface is 5 ° or less.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are rotated and moved relative to the plate-shaped glass base plate 10A around the rotation center A1.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are rotated about the rotation center A1 at the same angular velocity with the force of approximately the same magnitude applied to the outer cutter wheel 3 and the inner cutter wheel 4 downward.
  • the outer cut line 11 and the inner cut line 12 are formed on the upper main surface of the plate-shaped glass base plate 10A.
  • the outer cutter wheel 3 and the inner cutter wheel 4 are arranged on the same side with respect to the rotation center A1.
  • the present embodiment is not limited thereto, and the outer cutter wheel 3 may be disposed on the opposite side of the inner cutter wheel 4 with respect to the rotation center A1.
  • a portion outside the outer cut line 11 of the plate-like glass base plate 10A is heated. Then, due to the difference in thermal expansion, the outer scoring line 11 develops, and a split section that reaches the main surface (second main surface) opposite to the first main surface of the plate-like glass base plate 10A is formed. Is done.
  • the outer part of the plate-shaped glass base plate 10 ⁇ / b> A outside the inner cut line 12 is heated. Then, due to the difference in thermal expansion, the inner scissors 12 develop, and a fractured surface that reaches the main surface (second main surface) opposite to the first main surface of the plate-like glass base plate 10A is formed. Is done.
  • annular glass base plate 10B as shown in FIG. Is obtained.
  • the portion is pulled downward so that the main surface is not touched and scratched.
  • FIG. 11 is a diagram showing an example of a cross section of an annular glass base plate 10B.
  • the annular glass base plate 10 ⁇ / b> B has an outer peripheral end surface 13, an inner peripheral end surface 14, a first main surface 15, and a second main surface 16.
  • the outer peripheral end surface 13 is a fractured cross section in which the outer cut line 11 of the plate-like glass base plate 10 ⁇ / b> A has advanced to reach the second main surface 16.
  • the inner peripheral end surface 14 is a split section in which the inner cut line 12 of the plate-shaped glass base plate 10 ⁇ / b> A has advanced to reach the second main surface 16.
  • the first main surface 15 is a part of the first main surface in which the outer cut line 11 and the inner cut line 12 of the plate-like glass base plate 10A are formed.
  • the second main surface 16 is a main surface opposite to the first main surface 15 of the annular glass base plate 10B, and is a second main surface that is in contact with the table 2 of the plate-like glass base plate 10A. It is a part.
  • the outer periphery 15 ⁇ / b> A of the first main surface 15 is formed by the outer cut line 11.
  • the outer periphery 16A of the second main surface 16 is formed by the split section extending from the outer cut line 11 reaching the second main surface 16 of the plate-like glass base plate 10A.
  • the inner circumference 15 ⁇ / b> B of the first main surface 15 is formed by the inner cut line 12.
  • the inner periphery 16B of the second main surface is formed by the split section extending from the inner cut line 12 reaching the second main surface of the plate-like glass base plate 10A.
  • the outer cut line 11 and the inner cut line 12 are grown by reducing the tendency that the split section of the inner cut line 12 is inclined toward the center side of the glass base plate 10A.
  • ⁇ 13 is an angle formed by a straight line from the outer periphery 15A toward the center of the main surface 15 and an extension line of the outer peripheral end surface 13 in the cross section including the center line of the glass base plate 10B shown in FIG.
  • ⁇ 14 is an angle formed by a straight line extending from the inner periphery 15B toward the center of the first main surface 15 and an extension line of the inner peripheral end surface 14 in a cross section including the center line of the glass base plate 10B. Note that “substantially the same angle” means that the difference in angle between ⁇ 13 and ⁇ 14 is less than 10 °.
  • both the outer peripheral end surface 13 and the inner peripheral end surface 14 have shown the state inclined so that it might go to radial direction outward toward the 2nd main surface from the 1st main surface 15, If ⁇ 13 and ⁇ 14 are substantially the same angle, either of the outer peripheral end surface 13 and the inner peripheral end surface 14 may be perpendicular to the first main surface 15, or any of the outer peripheral end surface 13 and the inner peripheral end surface 14. Alternatively, the first main surface 15 may be inclined toward the second main surface 16 inward in the radial direction. However, it is more preferable that both the outer peripheral end face 13 and the inner peripheral end face 14 are perpendicular to the first main surface 15 because the process can be completed with the smallest machining allowance in the subsequent chamfering process.
  • the inner peripheral end surface 14 and the outer peripheral end surface 13 each include a split cross-section, and in cross-sectional view, with respect to the main surfaces of the inner peripheral end surface 14 and the outer peripheral end surface 13. It is a glass base plate whose angle difference is 10 ° or less. Since the angle difference is 10 ° or less, the processing efficiency in the chamfering processing of the annular glass base plate 10B can be increased, and the production efficiency of the annular glass substrate is increased. Note that the fractured surface can be specified by observing smooth irregularities on the surface when visually observed using a microscope having a magnification of about 10 times. In the process of manufacturing the magnetic disk glass substrate from the annular glass base plate 10B, the outer peripheral end surface 13 and the inner peripheral end surface 14 are subjected to chamfering processing and end surface polishing processing for mirror finishing by brush polishing.
  • Glass substrate manufacturing method Next, a method of manufacturing a magnetic disk glass substrate from the annular glass base plate obtained in the first embodiment and the second embodiment will be described.
  • chamfering is performed on an annular glass base plate by end surface grinding using a general-purpose grindstone (chamfering processing). Thereby, a ring-shaped (annular) glass substrate having a chamfered surface is generated.
  • main surface grinding processing is performed (grinding processing), and end surface polishing is performed on the flattened glass substrate (end surface polishing processing).
  • polishing is performed to the main surface of a glass substrate (1st grinding
  • second polishing is performed on the first polished glass substrate (second polishing process).
  • the glass substrate for magnetic disks is obtained through the above processing.
  • the angle between the outer cutter wheel 3 and the inner cutter wheel 4 satisfying the relationship of ⁇ 2> 0 and ⁇ 1 ⁇ 2 with the main surface of the first plane P1 is the second plane P2.
  • a plate-shaped glass base plate for example, a glass base plate of a glass material having a linear expansion coefficient of 65 ⁇ 10 ⁇ 7 / ° C. or less
  • 10A so as to have the same angle as the main surface.
  • the lifespan of the outer cutter wheel 3 and the inner cutter wheel 4 can be made equal, and the outer cutter wheel can be made equivalent. 3 and the inner cutter wheel 4 can be easily replaced at the same time, which increases the production efficiency of the glass substrate.
  • the outer cutter wheel 3 and the inner cutter wheel 4 in the first embodiment satisfy the contents of the second embodiment, that is, ⁇ 2> 0 and ⁇ 1 ⁇ 2, and
  • the outer periphery cutting line 11 and the inner periphery cutting line 12 are formed perpendicularly with respect to the 1st type
  • Table 4 shows the difference between the roundness of the outer periphery 15A of the first main surface 15 and the roundness of the outer periphery 16A of the second main surface 16.
  • the difference in roundness between Examples 1 to 3 and Example 6 was 100 ⁇ m or less.
  • the difference in roundness of Comparative Example 1 exceeded 100 ⁇ m.
  • the difference in roundness was 100 ⁇ m or less.
  • a plate-like glass base plate (reference example) having a linear expansion coefficient of 90 to 100 ( ⁇ 10 ⁇ 7 / ° C.), and a linear expansion coefficient of 55 to 65 ( ⁇ 10 ⁇ 7 / ° C.) plate-like glass base plate (Comparative Examples 1, 3-5, Examples 1-3 and 7-16), a linear expansion coefficient of 35 to 45 ( ⁇ 10 ⁇ 7 / ° C.) and a thickness of 1 mm
  • a plate-shaped glass base plate (Comparative Example 2, Example 4-6) was used.
  • the outer cutting wheel 11 and the inner cutting line 12 are formed on the plate-shaped glass base plate 10A using the outer cutter wheel 3 and the inner cutter wheel 4 and cleaved, whereby the outer diameter is about 66 mm and the inner diameter is about 19 mm.
  • An annular glass base plate 10B was prepared.
  • the first plane including the cutting edge ridge 31 of the outer cutter wheel 3 and the second plane including the cutting edge ridge 41 of the inner cutter wheel 4 are both perpendicular to the main surface of the plate-shaped glass base plate 10A.
  • the outer cutter wheel 3 and the inner cutter wheel 4 were brought into contact with the main surface of the plate-shaped glass base plate 10A so as to be perpendicular to the rotational radius direction.
  • Glass having a linear expansion coefficient of 90 to 100 is glass A having the following composition, and glass having a linear expansion coefficient of 55 to 65 ( ⁇ 10 ⁇ 7 / ° C.) is the glass B and wire below.
  • An expansion coefficient of 35 to 45 was prepared by appropriately adjusting from the following range of glass C.
  • Glass B Contains SiO 2 40 to 61, Al 2 O 3 15 to 23.5, MgO 2 to 20, CaO 0.1 to 40 in terms of% by mass on the oxide basis, and [SiO 2 ] + 0.43 ⁇ [Al 2 O 3 ] + 0.59 ⁇ [CaO] ⁇ 74.6 ⁇ 0 and [SiO 2 ] + 0.21 ⁇ [MgO] + 1.16 ⁇ [CaO] ⁇ 83.0 ⁇ 0 Silicate glass.
  • the Young's modulus is 87 GPa or more, the strain point is 680 ° C. or more, the average thermal expansion coefficient at 50 to 350 ° C. is 30 ⁇ 10 ⁇ 7 to 47 ⁇ 10 ⁇ 7 / ° C., and the mass based on oxide In terms of%, SiO 2 55 to 69, Al 2 O 3 17 to 27, B 2 O 3 0 to 3, MgO 0 to 20, CaO 2 to 20, SrO 0 to 2, BaO 0 to 2, SnO 2 0.
  • SiO 2 + Al 2 O 3 + MgO + CaO is 95 or more
  • MgO + CaO + SrO + BaO is 12 to 23
  • Tables 5 to 7 show ⁇ o1, ⁇ i1, ⁇ o2, ⁇ i2, ⁇ 1, and ⁇ 2 of the outer cutter wheel 3 and the inner cutter wheel 4 used.
  • Examples 10 to 12 and Examples 1 to 3 were compared, the value of ( ⁇ 2 ⁇ 1) was the same, but there was a difference in yield. Since Examples 1 to 3 have a relationship of “ ⁇ i1 + ⁇ o1 ⁇ i2 + ⁇ o2”, it is presumed that it is advantageous in terms of cutting resistance and has a high yield.
  • annular glass base plate As described above, the annular glass base plate, the manufacturing method of the annular glass base plate, the manufacturing method of the annular glass substrate, and the manufacturing method of the glass substrate for magnetic disk of the present invention have been described in detail. Of course, the present invention is not limited to the above-described embodiment, and various improvements and modifications may be made without departing from the spirit of the present invention.

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PCT/JP2016/089203 2015-12-28 2016-12-28 円環状のガラス素板、円環状のガラス素板の製造方法、円環状のガラス基板の製造方法、及び磁気ディスク用ガラス基板の製造方法 WO2017115871A1 (ja)

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MYPI2018701605A MY188163A (en) 2015-12-28 2016-12-28 Annular glass blank, method for manufacturing annular glass blank, method for manufacturing annular glass substrate, and method for manufacturing magnetic-disk glass substrate
CN201680067880.1A CN108292510B (zh) 2015-12-28 2016-12-28 圆环状的玻璃坯板及制造方法、圆环状的玻璃基板的制造方法和磁盘用玻璃基板的制造方法
SG11201804418PA SG11201804418PA (en) 2015-12-28 2016-12-28 Annular glass blank, method for manufacturing annular glass blank, method for manufacturing annular glass substrate, and method for manufacturing magnetic-disk glass substrate
JP2017559253A JP6385595B2 (ja) 2015-12-28 2016-12-28 円環状のガラス素板、円環状のガラス素板の製造方法、円環状のガラス基板の製造方法、及び磁気ディスク用ガラス基板の製造方法

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